The best cell to study is a real pancreatic beta cell. However, isolating these cells requires the better part of a day, so that in the absence of technical assistance, isolating the cells and recording from them on the same day is impossible. To gather preliminary leads, therefore, it seemed more productive to work with models of the beta cell, that is cell lines derived from tumors of beta cells. The advantage of cell lines is that they are easily maintained in culture and require minimum time for preparation. The experimental procedure we employ is "whole cell voltage clamp", an important component of the "patch clamp" suite of techniques. Five such cell lines were examined: beta-TC tet, beta TC6, beta IR WT -/-, MIN6, and R7T1. Five criteria were compared: resting membrane potential, size and prevalence of sodium, potassium (delayed rectifier), and calcium (high voltage activated) currents, and the signature glucose response. None of these lines was a perfect model beta cell. For example, only the beta TC tet line showed anything close to a prototypical glucose response, and this response was seen in only two out of 20 recordings. Because calcium currents are a major center of interest, a line such as the MIN6 was eliminated because the calcium currents were too small to be worthy of recording (less than 50 pico Amps). Preliminary tests of the endocannabinoid arachidonylethanolamide (AEA, 1 micromolar) showed depression of both the delayed rectifier and the high voltage activated calcium currents of the beta-TC tet line. However, as these depressions were not reversed by washing, it was impossible to determine with certainty that they were caused by AEA or were just "rundown", a decrease in cell responsiveness that sometimes accompanies conventional whole cell voltage clamp. The line R7T1 was selected for further study, and the delayed rectifier potassium current was selected as the first current of interest. The endocannabinoid 2- arachidonylglycerol (2-AG, 10 micromolar) clearly decreased the current by about 40%. Though extensive washing did not reverse this effect and the antagonist AM-251 was also ineffective, using the lipid scavenger bovine serum albumin (BSA, lipid free) followed by washing, completely reversed the depression. The ineffectiveness of AM- 251 suggested that the mediator of the depression was not the CB1 cannabinoid receptor, and that rather that the mediator was a something else, probably a perturbation of the lipid membrane. In support of this hypothesis, the potent cannabinoid agonist WIN 55,212-2 (1 micromolar) produced no depression of the delayed rectifier, though it did seem to produce a "rebound" effect on wash out. However, as that "rebound" was also seen when the enantiomer WIN 55,212-3 was tested, we conclude that the effect was also independent of cannabinoid receptors. Tests of 2-AG on calcium channels are still in progress. Though a depression in high voltage activated calcium currents is seen, it is not only irreversible by ordinary washing, but also with the aid of BSA. The "run down" effect is known to be particularly evident with calcium currents, and we believe that this is the main confound of the experiment. To by-pass rundown requires using the "perforated patch" technique. In the conventional whole cell patch technique, a gross rupture in the cell membrane under the rim of the patch pipette is created by suction so that the cytosol and the medium within the patch pipette are continuous. In the perforated patch technique, by contrast, the cell membrane is not ruptured, but instead an agent is included in the pipette solution, such as nystatin or amphotericin B, that creates molecular pores in the membrane that are selectively permeable to monovalent cations, thereby preserving the components of the cytosol from dilution by the pipette medium while permitting electrical conductivity. Whereas the perforated patch method is most benign in principle, in practice it is much more difficult than conventional whole cell recording. In addition to the well known delays required for perforation to occur (sometimes it never occurs), I find that the permeabilized membrane patch seems to be more susceptible to dielectric breakdown during voltage jumps, so that the patch seems to rupture, and as a consequence the membrane resistance takes a dramatic drop, possibly due to the diffusion of the nystatin or amphotericin B through the cytosol to the plasma membrane. These are difficult experiments that have so far yielded scant data.